Gas chromatography–mass spectrometry

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Gas chromatography–mass spectrometry (GC-MS) is an analytical method that combines the features of gas chromatography and mass spectrometry to identify different substances within a test sample. It is used for a wide range of applications, including drug detection, environmental analysis, and the identification of unknown samples.

Principle

GC-MS operates by separating the chemical mixture (the GC component) and then identifying the components at a molecular level (the MS component). The gas chromatograph vaporizes the sample and separates the various components based on their retention time. The mass spectrometer then ionizes the separated components and measures their mass-to-charge ratio.

Components

1. 1. 1. Gas Chromatography

The gas chromatography component consists of an injection port, a column, and a detector. The sample is injected into the injection port, where it is vaporized. The vaporized sample is then carried by an inert gas (the mobile phase) through the column, which contains a stationary phase. Different compounds in the sample interact differently with the stationary phase, causing them to elute at different times.

1. 1. 1. Mass Spectrometry

The mass spectrometry component consists of an ion source, a mass analyzer, and a detector. The separated compounds from the GC are ionized in the ion source, typically by electron ionization. The ions are then separated based on their mass-to-charge ratio in the mass analyzer. The detector records the ions, producing a mass spectrum that can be used to identify the compounds.

Applications

GC-MS is widely used in various fields due to its high sensitivity and specificity. Some common applications include:

• Forensic science: Detection of drugs and poisons in biological samples.
• Environmental analysis: Monitoring pollutants in air, water, and soil.
• Food safety: Detection of contaminants and residues in food products.
• Pharmaceuticals: Analysis of drug purity and identification of impurities.

Advantages

• High sensitivity and specificity.
• Ability to analyze complex mixtures.
• Quantitative and qualitative analysis.

Limitations

• Requires volatile or semi-volatile compounds.
• Sample preparation can be time-consuming.
• High operational costs.

Related Pages

• Chromatography
• Mass spectrometry
• Forensic toxicology
• Environmental monitoring
• Analytical chemistry

See Also

• Liquid chromatography–mass spectrometry
• High-performance liquid chromatography
• Tandem mass spectrometry